The peripheral nervous system of a human body consists of the nerves and ganglia outside of the brain and spinal cord. Its main function is to connect the central nervous system to the limbs and organs. Unlike the central nervous system, the peripheral nervous system is not protected by the bone of the spine and the skull, or by the blood-brain barrier, leaving it available for non-invasive, peripheral, electrical nerve stimulation.
Nerves may suffer functional defects due to normal wear and tear, physical injuries, infection, and/or the failure of blood vessels surrounding the nerves. Other defects occur with the inappropriate activation or inhibition of somatic and autonomic pathways. These functional defects may be accompanied by pain, numbness, weakness, and in some cases, paralysis. In other cases, defects may cause undesirable initiation or suppression of physiological functions such as muscle contraction. Problems may include urinary or fecal incontinence. For example, with urinary incontinence, daily physical activities such as laughing, coughing, and sneezing may result in involuntary urination. Similarly, inappropriate contraction and relaxation of muscles that control bladder functioning may result in unplanned and undesired urination.
OAB is a urological condition defined by a set of symptoms that include urgency, with or without urge incontinence, and is usually accompanied by frequency and nocturia. Frequency is defined as urinating more than 8 times a day. In people with OAB, the layered, smooth muscle that surrounds the bladder (detrusor muscle) contracts spastically, sometimes without a known cause, which results in sustained, high bladder pressure and the urgent need to urinate. Normally, the detrusor muscle contracts and relaxes in response to the volume of urine in the bladder and the initiation of urination. People with OAB often experience urgency at inconvenient and unpredictable times and sometimes lose control before reaching a restroom.
Accordingly, urge incontinence and overactive bladder interfere with work, daily routine, and the like; causes embarrassment; and can diminish self-esteem and quality of life.
There are a variety of treatment options for OAB. Conservative treatment starts with bladder training techniques, such as education, timed voiding, restriction of fluid intake, and distraction/relaxation. These can be combined with pelvic floor training exercises that are intended to strengthen and support the pelvic floor muscles. A number of medications are effective for treating OAB. Anticholinergic (antimuscarinic) agents and agents with mixed anticholinergic and bladder wall effects are widely prescribed for OAB. Numerous randomized, controlled trials and systematic reviews have established that these drugs have efficacy over placebo, but the magnitude of benefit in reducing OAB symptoms is modest; a substantial number of patients will not achieve adequate symptom relief, and there are relatively high rates of adverse effects. For patients with OAB refractory to standard treatments, more invasive treatment options are available, such as intravesicular administration of botulinum toxin A, sacral nerve stimulation, or augmentation cytoplasty.
Another technique for overcoming the urge incontinence or OAB involves stimulating either the sacral or tibial nerve by using an electric or magnetic impulse. This is commonly referred to as transcutaneous or percutaneous nerve stimulation. One such electro-medical device capable of providing the required stimuli is commonly referred to as an implantable Pulse Generator (IPG). An IPG typically includes one or more electrodes, an electrical pulse generator, a battery, and a housing. The electrical pulse generator generates a waveform having a specific shape, form, and frequency range capable of stimulating a target nerve. When the electrodes receive the waveform from the generator, they draw energy from the battery and generate an electric field of suitable strength to stimulate the target nerve.
IPGs are typically used for stimulating the sacral nerve and have proven to be somewhat effective. One of the problems associated with IPGs, however, is that implanting the device is invasive, and may cause undesirable complications during and after implantation. Documented complications associated with the implantation procedure include bleeding, infection, or tissue damage. Documented complications after the implantation procedure include generator and/or lead failures. Sometimes a complication may require removal of the device, and re-implantation of a new device.
Another technique commonly used to provide the required impulse is electro-acupuncture nerve stimulation. Electro-acupuncture nerve stimulation involves passing a small electric current between pairs of acupuncture needles. The needles may provide electrical nerve stimulation percutaneously or subcutaneously. Both approaches involve inserting needles (also called the electrodes) into the prescribed acupuncture or trigger points so that the external parts of the needles can be secured against the skin of the patient. Both approaches require the patient to go to a clinic for clinician insertion of the needles into the skin. Additionally, patients have been known to experience some discomfort with these approaches. Furthermore, the known device exhibits some difficulty in use and precision control of the procedure because it is impossible to change a position of the inserted electrode in the body without compromising needle sterility or without removing the whole electrical assembly.
Posterior tibial nerve stimulation (PTNS) is the least invasive form of neuromodulation used to treat OAB and the associated symptoms of urinary urgency, urinary frequency and urge incontinence. PTNS is a type of neuromodulation therapy that uses electrical stimulation to target specific nerves in the sacral plexus that control bladder function. Specifically, tibial nerve stimulation targets the nerves of the pelvic floor with gentle electrical impulses to alter the activity of the bladder. The treatment targets the sacral plexus from an accessible minimally invasive entry point into the nervous system. These urinary symptoms may also occur with interstitial cystitis and following a post-radical prostatectomy. Outside the United States, PTNS is also used to treat fecal incontinence. PTNS has been shown to be effective as a primary therapy. However, treatment for Overactive Bladder and Fecal Incontinence many times begins with conservative therapies including pharmacology. Nearly 80% of patients discontinue use of drugs within the first year, many due to adverse side-effects. Neuromodulation is emerging as an effective modality to treat patients who are not successful with pharmacologic methods.
Since the introduction of PTNS, many published studies have demonstrated PTNS efficacy in treating OAB symptoms. Ridout et al. in W. J. Obstet Gynaecol 2010; 30(2) published a literature review evaluating evidence of PTNS for overactive bladder syndrome. The authors found that PTNS may have a role as a useful, minimally invasive treatment option in medically refractory OABS with a 60-81% response rate. However, there is insufficient data to advocate PTNS as a first-line treatment due to its cost and long-term treatment regimen. This invention addresses the cost and treatment method by providing an alternative means of stimulation without breaking the skin.
In 2010, Peters et al. in the Journal of Urology Vol. 183 published results of a randomized clinical trial (RCT) comparing PTNS with sham treatment in patients with OABS. Two hundred and twenty (220) adults with OABS were randomized 1:1 to 12 weeks of treatment with weekly PTNS or sham therapy. Overactive bladder and QOL questionnaires, as well as 3-day voiding diaries were completed at baseline and at 13 weeks. Subject global response assessments were completed at week 13. Results showed PTNS subjects had statistically significant improvement in bladder symptoms with 54.5% reporting moderately or markedly improved responses compared to 20.9% of sham subjects from baseline (p<0.001). Voiding diary measures after 12 weeks found PTNS subjects had significant improvements in frequency, nighttime voids, voids with moderate to severe urgency and urinary urge incontinence episodes compared to sham. Based on the results, researchers concluded PTNS is safe and effective in treating overactive bladder symptoms.
MacDiarmid et al. in the Journal of Urology Vol. 183 described the results of the second phase of a study of PTNS for OAB. The initial study period was 12 weeks. Thirty-two subjects completed 6 additional months of PTNS therapy and 25 completed the full 12 months. Outcome measures included voiding diary data, overactive bladder questionnaires, global response assessments and safety assessments. Patients received an average of 12.1 treatments during an average of 263 days, with a mean of 21 days between treatments. Global response assessments showed sustained improvement from 12 weeks at 6 and 12 months, with 94% and 96% of responders, respectively. The authors found the statistically significant improvements at 12 weeks demonstrated excellent durability through 12 months.
The present invention addresses the issues of the prior art by treating urge incontinence or OAB using a transcutaneous electrical nerve stimulation device. A method is provided for same.
The current accepted form of providing nerve stimulation is a minimally invasive procedure via an office based implantation of a stimulation device. Typically, PTNS is a 30 minute office based treatment via a needle electrode inserted near the tibial nerve, which carries electric impulses from a hand-held stimulator to the sacral plexus. Even though the therapy can be clinically effective with few side effects, the current invasive means of administration causes it to be expensive mainly due to requiring weekly visits for administration by a trained professional. Furthermore, as discussed earlier, difficulty in use and precision control of the therapy delivery device and some patient discomfort have been known.
The posterior tibial nerve is a mixed sensory and motor nerve containing fibers originating from the lumbar and sacral areas of the spine. The sacral nerves modulate the somatic and autonomic nerve supply to the bladder and urinary sphincter. The idea of stimulating the tibial nerve was based on the traditional Chinese practice of using acupuncture points over the common peroneal or posterior tibial nerves to affect bladder activity. The posterior tibial nerve projects to the sacral spinal cord in the same area where bladder projections are found. These are the areas where the therapeutic effect of neuromodulation of the bladder through posterior tibial nerve stimulation takes place. Even though the exact mechanism of action of neuromodulation is unclear, the potential benefit of percutaneous or transcutaneous posterior tibial nerve stimulation is that it may achieve the same neuromodulatory effect as sacral nerve stimulation through a less invasive route.
The present invention provides a safe, reliable, efficacious and convenient means for treating the condition known as urge incontinence or OAB. As discussed in the previous section, transcutaneous electrical nerve stimulation is a proven therapy. This invention packages this for patient convenience, and is essentially painless and simple to use. Most importantly, the device is non-invasive. The device may be strapped (or otherwise adhered) around or on the ankle, or anywhere along the leg wherein the tibial nerve may be electrically stimulated transcutaneously. The device remains in place as the patient ambulates about and outside of the home. Additionally, the patient may secure the device in place without clinician or clinic assistance. This allows the patient with this condition to benefit from the device in the comfort of his/her own home.
The non-invasive nature of the invention further makes it simple to use and does not require administration by a trained professional, in contrast to other minimally invasive devices on the market. The non-invasive nature also means that administration can be performed without requiring the patient to come into a clinic. This reduces the overall cost of therapy and makes it accessible to a much larger population who may have previously been unable to afford a required weekly minimally invasive PTNS procedure. The device conforms to the contours of the region around the ankle of the foot to ensure a low impedance electrical conduit between the electrodes and the skin. This is important to ensure maximum stimulation.
Electro-acupuncture or nerve stimulation devices have been proven effective for the control of nausea and vomiting. An example of an electro-acupuncture device is described in U.S. Pat. No. 4,981,146 to Bertolucci, marketed under the trademark Relief-Band®, for control of nausea and vomiting, is worn on the wrist like a wristwatch, with a watch-like housing which is positioned on the underside or planar surface of the wrist. A patient suffering from nausea or vomiting (from motion sickness, morning sickness, chemotherapy, or anesthesia) can strap the device onto their wrist and turn it on. When turned on, the device emits an electrical stimulation pulse over the P6 acupuncture point (corresponding to the superficial course of the median nerve through the wrist). Within several minutes, most patients experience a substantial relief of nausea. Accordingly, there is a need for non-invasive nerve stimulation devices whereby electricity is passed through electrodes to stimulate nerves strategically located within the body, such as a foot or a leg, for electro-acupuncture or acupuncture treatment of urination related maladies, including non-limiting examples such as overactive bladder or incontinence. However, the anatomical structure of the ankle, within which the tibial nerve is positioned, is quite unique and different from that of the wrist. Unlike the wrist, the ankle comprises a boney projection called the malleous which protrudes outwardly from both the lateral and medial sides of the ankle. In addition, the unique bone, ligament and tendon structure of the ankle make adherence of a device difficult. In particular, the area of depression located between the Achilles tendon and the calcaneus bone in addition to the boney malleous boney projection of the ankle make it particularly difficult to adhere a device to the exterior surface of the ankle so that effective stimulation of the tibial nerve can be achieved. Therefore, what is needed is a non-invasive transcutaneous nerve stimulation device that is conformal to the unique geometry and contours of the ankle region so that effective stimulation of the tibial nerve in treating over active bladder can be achieved.